vBulletin LTS

Go to your headinclude template
(AdminCp -> Styles & Templates -> Edit Templates -> headinclude)

Seacrh for:

Code:

<!-- / CSS Stylesheet -->

Below, add:

Code:

<script type="text/javascript">
/***********************************************
* Gradual Highlight image script- © Dynamic Drive DHTML code library (www.dynamicdrive.com)
* This notice MUST stay intact for legal use
* Visit Dynamic Drive at http://www.dynamicdrive.com/ for full source code
***********************************************/
var baseopacity=30
function slowhigh(which2){
imgobj=which2
browserdetect=which2.filters? "ie" : typeof which2.style.MozOpacity=="string"? "mozilla" : ""
instantset(baseopacity)
highlighting=setInterval("gradualfade(imgobj)",50)
}
function slowlow(which2){
cleartimer()
instantset(baseopacity)
}
function instantset(degree){
if (browserdetect=="mozilla")
imgobj.style.MozOpacity=degree/100
else if (browserdetect=="ie")
imgobj.filters.alpha.opacity=degree
}
function cleartimer(){
if (window.highlighting) clearInterval(highlighting)
}
function gradualfade(cur2){
if (browserdetect=="mozilla" && cur2.style.MozOpacity<1)
cur2.style.MozOpacity=Math.min(parseFloat(cur2.style.MozOpacity)+0.1, 0.99)
else if (browserdetect=="ie" && cur2.filters.alpha.opacity<100)
cur2.filters.alpha.opacity+=10
else if (window.highlighting)
clearInterval(highlighting)
}
</script>

Save & Close.

Now go to your style options:
(vBAdminCp -> Styles & Templates -> Styles Manager -> Your style Name --> All style Options -> Go!)
In Additional CSS Definitions (second box), add:

Code:

.gradualshine{
filter:alpha(opacity=30);
-moz-opacity:0.3;
}

Save & Close.
Now, go to add a new Replacement Variable:
(vBAdminCp -> Styles & Templates -> Styles Manager -> Your style Name --> Replacement Variables -> Add -> Go!):

Search for text: <img
Replace with text: <img class="gradualshine" onMouseover="slowhigh(this)" onMouseout="slowlow(this)"

Save!